The present invention relates to a steering return control apparatus and method of MDPS (Motor Driven Power Steering), and more particular, to a steering return control apparatus and method of MDPS, which is capable of minimizing a slight sense of difference in an on-center region when a steering wheel is returned after a vehicle was steered at a large steering angle during driving.
In general, MDPS represents a system that assists handling by providing an assist torque in a steering direction of a driver, using an electric motor. The MDPS can autonomously control the operation of the electrical motor, depending on a traveling condition of a vehicle, thereby improving the steering performance and steering feel.
When determining that the vehicle was turned to a desired extent after a steering input was applied to turn the vehicle, the driver may release the steering wheel. In this case, the steering wheel is returned to the center by its return operation. The return operation of the steering wheel is performed by self alignment torque of a tire. Typically, when the vehicle is turned at a velocity of 5 km/h to 30 km/h, the return operation can be usefully applied. However, the self alignment torque applied to the steering wheel is not enough to return the steering wheel to the center because the frictional behavior of the steering system causes a remaining steering angle.
Thus, a separate function of assisting the return operation is inevitably provided to completely return the steering wheel to the center. Therefore, the MDPS applies a return torque which is calculated based on a steering angle, and assists the return operation of the steering wheel, thereby improving the return performance.
The related art is disclosed in Korean Patent Publication No. 2010-0114995 published on Oct. 27, 2010 and entitled “Steering return control method of MDPS”.
In the damping logic of the conventional MDPS, however, when a damping amount is adjusted for a fast return performance of the steering wheel, an overshoot may occur in an on-center region. When the damping amount is adjusted to reduce an occurrence of overshoot, the return velocity of the steering wheel may be lowered. Therefore, the damping amount in the on-center region is properly adjusted. However, when a driver turns the steering wheel at a similar velocity to the return velocity of the steering wheel, a slight sense of difference may occur in the on-center region.